1. Field of the Invention
The present invention generally relates to an IC card, more particularly to a thinner IC card which accommodates more electronic components more compactly.
2. Description of the Prior Art
IC cards based on PCMCIA specification have been now widely used.
FIG. 14 is a perspective view showing an external appearance of a conventional IC card. FIG. 15 is an exploded view of the IC card shown in FIG. 14. FIG. 16 is a cross section of the IC card shown in FIG. 14 cut along the plane XVI--XVI.
In FIGS. 14-16, an IC card 50 includes a U-shaped frame 51 made of plastic for example, metal panels 52a and 52b, a connector 53, made of plastic for example, which has a plurality of terminals 54 insert-molded therein so as to protrude inside of IC card 50, and a printed-circuit board 55 with electronic components 56 mounted on both surfaces thereof.
Inner tip ends of terminals 54 of connector 53 are formed so as to insert one side of board 55 along which a plurality of connecting tips are printed and, when inserted, electrically connect lines of board 55 with those of the external system, respectively. The combined connector 53 and printed-circuit board 55 are coupled with frame 51 so that the connector and the frame contain the printed-circuit board. Combined frame 51 and connector 53 containing printed-circuit board 55 connected to terminals 54 of the connector are sandwiched between metal panels 52a and 52b through adhesive sheets 57a and 57b, respectively.
Upon assembling an IC card as shown in FIGS. 14-16, printed-circuit board 55, with electronic components mounted on it, is connected to connector 53 by means of connector terminals 54, and then connector 53 is fit to frame 51. Then adhesive sheets 57a and 57b are pasted to metal panels 52a and 52b, respectively. Metal panels 52a and 52b are fixed, with heat and pressure, by means of adhesive sheets 57a and 57b, respectively, to frame 51 combined with connector 53 and printed-circuit board 55 from the top and the bottom. In the process of assembling IC cards adhesive sheets 57a and 57b must be pasted to metal panels 52a and 52b in considerable precision. Further, the amount of heat and pressure required to fix the metal panels to the frame must also be controlled precisely. Thus, manufacturing conventional IC cards requires the greatest attention in the assembly process, which results in higher manufacturing cost.
As increasingly more electronic components are mounted on a conventional IC card of a fixed size of 85.6 mm.times.54.0 mm.times.3.3 mm, for example, a multilayer printed-circuit board has been used to accommodate them. The structure of a multilayer printed-circuit board with electronic components mounted thereon and the mounting method are disclosed in Japanese Patent Laid-Open Publication HEI 3-280496. The structure disclosed in that publication includes stacked printed-circuit boards with common through holes in them and a plurality of electronic components which are inserted in each through hole and mounted on top of one another. Only "bonding" is allowed in this configuration, and an electronic component with a molded package cannot be mounted. Ordinary soldering such as reflow soldering cannot be used either. This structure does not allow printed-circuit boards to have electronic components initially mounted on them and then to be stacked on top of one another.